Second seed Nadal, the dominant force in men's tennis this year and soon to be ranked number one, was given a stern test in the opening set before Andreev wilted in the muggy conditions.

Andreev, who reached the third round in Athens four years ago, did well to stay with Nadal in the opening six games but cracked at 3-3 when a fierce baseline exchange ended with him dropping serve to trail 4-3.

Nadal had problems at 5-4, when some huge Andreev forehands carved out four break points, but the Spaniard dug himself out of trouble with some help from his wasteful opponent.

A deflated Andreev dropped serve twice early in the second set and Nadal closed out the victory to set up a quarter-final clash with Austria's Jurgen Melzer, a straight sets winner against Taiwan's Lu Yen-Hsun.